1. Field of the Invention
The present invention relates to a pulse wave measuring apparatus, and a biological wave analysis program product. More particularly, the present invention relates to a pulse wave measuring apparatus and a biological wave analysis program product that can calculate the early systolic component and late systolic component properly from an original waveform.
2. Description of the Background Art
Blood pressure is the pressure exerted by the blood flow, generated by the contraction and expansion of the heart upon the inner wall of the artery. Systolic pressure that is the blood pressure corresponding to the systole of the heart and diastolic pressure that is the blood pressure corresponding to the diastole of the heart constitute blood pressure. The pulse pressure wave constituting the intra-arterial pressure is a superposed wave of the early systolic component (traveling wave) generated by ejection of blood from the heart and the late systolic component (reflected wave) generated by the reflection from mainly arterioles and capillary vessels. An inflection point is present between these two components.
The waveform of such a pulse wave changes as the measurement site becomes more distal. Specifically, the late systolic component becomes lower than the early systolic component in proportion to a more distal measurement site.
Japanese Patent Laying-Open No. 7-39530 discloses an automatic sphygmomanometer automatically analyzing the early systolic component and late systolic component by obtaining the wave of fourth derivative of the original waveform of a pulse wave.
Since the process of obtaining the late systolic component based on the original waveform and the wave of fourth derivative is employed, the conventional automatic sphygmomanometer disclosed in the aforementioned Japanese Patent Laying-Open No. 7-39530 has the problem that the late systolic component can not be obtained in the case where there are so many characteristic points of the wave of fourth derivative of the original waveform that the characteristic point is indefinite, or in the case where the method of obtaining the late systolic component used is a method directed to a measurement site differing from the relevant measurement site of the waveform. There is also the problem that the waveform of the pulse wave changes depending upon the generated timing and level of the reflected wave corresponding to the hardness of the vascular wall even if the pulse wave is measured at the same place.